Dock seals and dock shelters are used to provide a weather seal between a dockboard the rear end of a truck parked in front of the dock.
Dock seals are normally composed of a resilient material and are mounted along the sides and top of the doorway in the dock. As the truck backs toward the dock, the rear end of the truck will engage the dock seal to compress the seal and provide a weather seal between the truck and the dock.
In some cases, dock seals are composed of inflatable bags, while in other instances the dock seal may comprise resilient pads or cushions.
While the dock seal provides an effective weather seal between the truck and the dock, the dock seal, when in the sealing position, protrudes inwardly into the truck and encroaches upon the access opening. Because of this, the protruding edge of the dock seal is frequently engaged by cargo or fork lift trucks which can cause damage to the seal and substantially reduce the service life of the dock seal.
Dock shelters, instead of sealing against the rear end of the truck as in the case of a dock seal, are adapted to engage the sides and top of the truck. Certain dock shelters are composed of flexible panels which are positioned to be engaged by the truck, and due to their resilient nature, engage the sides and top of the truck. Other types of dock shelters are composed of movable panels which can be moved either by mechanical or fluid means from a storage position to a sealing position where the panels engage the outer truck surfaces.
By engaging the outer surface of the truck, dock shelters do not encroach or restrict the access opening to the interior of the truck, but dock shelters, in general, do not provide as complete a weather seal as dock seals, particulary at the upper corners where the side panels are joined to the top panel of the dock shelter. This is due primarily to the fact that the trucks have varying dimensions and both the top panel and side panels can be at different angles of inclination when in the sealing position.
Further, both seals and shelter are normally composed of fabric which is prone to wear from repeated engagement with the rear ends of trucks.